Display systems may include a beam splitter, a quarter wave retarder and a reflective polarizer. U.S. Pat. No. 7,242,525 (Dike) describes an optical system that projects a real image into space and includes one or more features located along the optical path that enhance the viewability of the real image. The optical system includes a converging element for converging a portion of source light so as to form the real image.
U.S. Pat. No. 6,271,969 (Mertz) describes an optical collimating assembly for imaging light from a display. The optical assembly includes first and second linear polarization fillers having polarization directions that are orthogonal to one another. A folded imaging assembly that includes a first beam splitter, a first ¼ wave plate, and a second beam splitter is located between the polarization filters.
U.S. Pat. No. 8,780,039 (Gay et al.) describes an optical system for varying the shape of a surface in which an image displayed by the display device is perceived. The optical system comprises first and second spaced-apart partial reflectors, at least one of which is switchable between a first non-flat shape and a second different shape, which may be flat or non-flat. The reflectors, together with polarization optics, provide a light path such that light from the display is at least partially transmitted by the first reflector, partially reflected by the second reflector, partially reflected by the first reflector and partially transmitted by the second reflector.
Reflective polarizers may be multilayer optical films. U.S. Pat. No. 6,916,440 (Jackson et al.) describes a process for stretching multilayer optical films in a uniaxial fashion, U.S. Pat. No. 6,788,463 (Merrill et al.) describes post-formed multilayer optical films.